The best solution they have thought of until now is to have a competition, not very ingenuous, isn't it?
What google should do is allow every user who models a building to advertise on its walls within google goggles. Building walls, basically, are just a type of advertising real-estate like websites and tv-commercial time. this way, would be advertisers and "land-grabbers" will get into a modeling frenzy, exactly like what happens when any new real-estate like market opens up (see domain names).
They could make a crowdsourcing voting app to filter out building spammers and provide the advertisers only a percentage of the income from ads, exactly like they do with adsense.